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well i'm about done removing the head gasket residue off my block and was looking at the funk inside the block (all the rust) and need to know if there is something i can put in there to let it soak and flush it out. the block is on a stand, so i won't need to run the chemicals thru the entire cooling system. also, shouldn't that drain plug on the driver side actually be functional to drain the block? i had to drain it from the knock sensor cuz nothing came out of the "drain plug".

Each drain plug drains only one side of the block. If you didn't drain the coolant out of the driver's side, then..... it's still there.

Take a coat hanger wire or something and rod the pass side hole out, in the upward direction. You'll get another gallon of coolant out of it.

The only way to drain the pass side of the block, is to take the knock sensor out of the drain hole that it lives in. That's what you're supposed to do.

Those 2 drain holes have been in SBC blocks since 1955. They just didn't realize at the time that the pass side one was for the knock sensor, they only "discovered" that fairly recently, in 81 or whenever the first CC carb V8s came out. It's funny how people nowadays somehow think that older blocks might not have that hole, or they call it the "knock sensor port" instead of coolant drain.

It is not sealed. It's blocked from large acculmulations of rust and scale and other foreign matter.

As mentioned above, all SBC motors for all time, have had one drain plug on each side of the block. Yours isn't the only special one in the whole universe whose drain plug is not a drain plug. Believe that.

If you don't un-block it, the one bank of cyls will not drain.

Go rod it out with a coat hanger, or a drill bit if the coat hanger doesn't get it. It's a drain plug, make it drain, and get all the coolant out.

As far as rust removal, once you get the plug out and the block torn down including all the freeze plugs out of it (which by the way will enable you to see down through the water jacket to the drain plug holes), take it to the quarter car wash; blast the hell out of all the collant jackets, then put some CLR or something of that nature in them, wait an hour or so, then blast it some more; keep doing that until you can see metal around the cyls again.

ok - well thanks for the insight. i was planning on keeping the rotating assy. in the block. i basically broke it down to fix all the leaks and have the heads redone. don't want to break it all the way down unless i absolutely have to. i'll clear the "plug" out and go from there.